Backlash is only one of the parameters used in setting up a rear end. You will get all the specs for pinion depth and backlash along with the new gears. For an installation kit that will make the job go much easier, I would go to Jegs or Summit Racing. You will also need a dial indicator with a magnetic base. Be prepared to spend an entire day doing this and maybe the whole weekend if you've never done it before. I will clue you in right now, there is no "turning torque" on setting up new gears. There is a "Crush Collar" that is installed on the pinion shaft that will take up the slack between the inner races on the pinion. It is a certified cast-iron ****** to get exactly right..
In other words - setting up gears is not easy work. You may be well advised to find a good speed-shop in your area and pay someone else to do it for you..